Concrete retaining wall blocks are used to build any number of landscape structures, including soil retention walls, for example. These structures are generally formed by stacking retaining wall blocks on top of one another in successive courses. During assembly of such retention or retaining walls, loose dirt often finds its way onto surfaces of the blocks. When the next course is placed on top of the already placed blocks, the presence of dirt or other debris may cause the lower surfaces of the blocks of the upper course to not be flush with the upper surfaces of the blocks of lower course. Also, the blocks may formed with a slight warp such that the upper and lower surfaces may not be planar but are slightly curved (e.g., the lower surface may be slightly convex).
The presence of dirt and/or warping may result in the upper and lower surfaces of the blocks not being flush or planar relative to one another, which can create undistributed or concentrated point loads on the blocks. Such loads can become large (e.g., depending an amount of weight being retained or on a height of an assembled wall). In some instances, such unevenly distributed loads may cause vertical cracks or break the retaining wall blocks, compromising the structural integrity of the retaining wall.